I totally understand little boys who love science. All of mine so far are wired this way! I think little boys just love to do, do, do!
And I certainly understand little boys who love to be read to about anything science related. So, with your little guy I can see adding additional readings if he loves science! 
The only reason I wanted to clarify in this thread about the science in general is that this question of whether HOD science is "enough" has come up on the board quite a bit, and I've never weighed in and explained the reasoning behind what we do in this area at Heart of Dakota.
I know not everyone may agree with our philosophy on every subject area, and we certainly do not have a monopoly on the ONE right answer. But, I did want to mention that from a state standard perspective we have included what is required in the area of science.
In order to explain our selection of the CLP science text, first it was important to us that (from a Biblical perspective) we lay a foundation in science that shows all of creation points to the Creator. Second, we wished to cover all required branches of science to give a general overview in life, physical, and earth science. Third, we desired to make the science portion of our programs economical, so homeschool parents from all incomes could afford to have a Christ-Centered education. So, all of those things played into our selecting Christian Liberty Press's science text.
One final detail we actually also had to weigh is how not to turn kids off to science by requiring too much of non-sciency kids, as that is one of the most common reactions kiddos have to science as they get older. So, if your little guy is excited about science that is a GOOD thing.
Only you know what books are best for your family, and through homeschooling you are in a wonderful position to tweak things to suit your family's needs. So, you will know best what your little guy finds appealing. Every family is different.
I am glad you are getting a chance to enjoy the rest of "Little Hearts..." though. We are loving it with our third son this year as well! Blessings,
Carrie
Since this is a common topic though and the quality of the science in our guides was being called into question, I wanted to weigh in and give a little background on why we chose to structure the science the way we did. 